Signal processing apparatus, and apparatus and method for driving gyro sensor using signal processing apparatus

ABSTRACT

A signal processing apparatus includes: a clock generator configured to generate a clock signal having a phase based on a phase of an input signal; a phase modulator configured to shift the phase of the clock signal to generate a phase-shifted clock signal; and a signal synthesizer configured to synthesize the phase-shifted clock signal and the input signal to generate a synthesized signal, wherein the phase modulator is configured to determine a value by which to shift the phase of the clock signal based on an amplitude of the input signal and an amplitude of noise included in the input signal.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 USC 119(a) of Korean PatentApplication No. 10-2015-0037318 filed on Mar. 18, 2015 in the KoreanIntellectual Property Office, the entire disclosure of which isincorporated herein by reference for all purposes.

BACKGROUND

1. Field

The following description relates to a signal processing apparatus, andan apparatus and a method of driving a gyro sensor using the signalprocessing apparatus.

2. Description of Related Art

In general, in order to improve sensitivity to a signal, a technologythat improves a signal-to-noise (S/N) ratio is used. For example, byimproving the S/N ratio, performance of a gyro sensor may be improved.Therefore, signal processing technology for improving the S/N ratio ofgyro sensors is desirable.

A noise-concealing method using a phase difference between a phase of asignal and a phase of noise may be considered as a method for improvinga S/N ratio. However, since the phase difference may not be uniform, aproblem may occur in which the S/N ratio is deteriorated.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

According to one general aspect, a signal processing apparatus includes:a clock generator configured to generate a clock signal having a phasebased on a phase of an input signal; a phase modulator configured toshift the phase of the clock signal to generate a phase-shifted clocksignal; and a signal synthesizer configured to synthesize thephase-shifted clock signal and the input signal to generate asynthesized signal, wherein the phase modulator is configured todetermine a value by which to shift the phase of the clock signal basedon an amplitude of the input signal and an amplitude of noise includedin the input signal.

The clock generator may be configured to generate the clock signal usinga self-oscillation loop such that the phase of the clock signal is thesame as the phase of the input signal.

The signal processing apparatus may further include a low-pass filterconfigured to perform low-pass filtering on the synthesized signal.

According to another general aspect, an apparatus for driving a gyrosensor includes: a clock generator configured to generate a clock signalhaving a phase based on a phase of a driving signal; a phase modulatorconfigured to shift the phase of the clock signal to generate aphase-shifted clock signal; a signal synthesizer configured tosynthesize the phase-shifted clock signal to generate a synthesizedsignal; and a low-pass filter configured to perform low-pass filteringon the synthesized signal.

The clock generator may include a phase shifter configured tophase-shift the driving signal by 90°. The phase shifter may beconfigured to phase-shift a feedback signal including drivingdisplacement information of the gyro sensor by 90°, and feed back thephase-shifted feedback signal to the driving signal to generate theclock signal.

The phase modulator may include an amplifier configured to amplify theclock signal generated by the clock generator. The phase modulator maybe configured to perform phase correction such that the phase of thedriving signal sensed when the gyro sensor is stopped and the phase ofthe clock signal have a phase difference of 90°. The phase modulator maybe configured to perform the phase correction such that the phase of thedriving signal sensed when the gyro sensor is rotated and the phase ofthe clock signal have a phase difference of 0°.

The apparatus may further include a sensor configured to sense drivingdisplacements of three axes of the gyro sensor, wherein the phasemodulator is configured to independently shift the phase of the clocksignal for the three axes, and the signal synthesizer is configured tosynthesize corresponding components of the driving signal for the threeaxes with the phase-shifted clock signal.

The phase modulator may be configured to determine a value by which toshift the phase of the clock signal based on an amplitude of the drivingsignal and an amplitude of noise included in the driving signal.

According to another general aspect, a signal processing methodincludes: generating, at a clock generator, a clock signal having aphase based on a phase of an input signal; shifting, at a phasemodulator, the phase of the clock signal to generate a phase-shiftedclock signal; combining phase-shifted clock signal and the input signalto generate a combined signal; and performing low-pass filtering on thecombined signal.

The combining of the phase-shifted clock signal and the input signal mayinclude multiplying the phase-shifted clock signal and the input signal.

The input signal may be generated by a gyroscope.

The method may further include generating the clock signal using aself-oscillation loop.

The phase modulator may be configured to determine a value by which toshift the phase of the clock signal based on an amplitude of the inputsignal and an amplitude of noise included in the input signal.

Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating a signal processing apparatus, accordingto an embodiment.

FIG. 2 is a view illustrating an apparatus for driving a gyro sensor,according to an embodiment.

FIG. 3 is a graph illustrating a signal when the gyro sensor is rotated,and a clock, according to an embodiment.

FIG. 4 is a graph illustrating a signal when the gyro sensor is stopped,and a clock, according to an embodiment.

FIG. 5 is a graph illustrating a phase distortion of a signal when thegyro sensor is stopped, according to an embodiment.

Throughout the drawings and the detailed description, the same referencenumerals refer to the same elements. The drawings may not be to scale,and the relative size, proportions, and depiction of elements in thedrawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader ingaining a comprehensive understanding of the methods, apparatuses,and/or systems described herein. However, various changes,modifications, and equivalents of the methods, apparatuses, and/orsystems described herein will be apparent to one of ordinary skill inthe art. The sequences of operations described herein are merelyexamples, and are not limited to those set forth herein, but may bechanged as will be apparent to one of ordinary skill in the art, withthe exception of operations necessarily occurring in a certain order.Also, descriptions of functions and constructions that are well known toone of ordinary skill in the art may be omitted for increased clarityand conciseness.

The features described herein may be embodied in different forms, andare not to be construed as being limited to the examples describedherein. Rather, the examples described herein have been provided so thatthis disclosure will be thorough and complete, and will convey the fullscope of the disclosure to one of ordinary skill in the art.

Throughout the specification, it will be understood that when anelement, such as a layer, region or wafer (substrate), is referred to asbeing “on,” “connected to,” or “coupled to” another element, it can bedirectly “on,” “connected to,” or “coupled to” the other element orother elements intervening therebetween may be present. In contrast,when an element is referred to as being “directly on,” “directlyconnected to,” or “directly coupled to” another element, there may be noelements or layers intervening therebetween. Like numerals refer to likeelements throughout. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be apparent that though the terms first, second, third, etc. maybe used herein to describe various members, components, regions, layersand/or sections, these members, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one member, component, region, layer or section fromanother region, layer or section. Thus, a first member, component,region, layer or section discussed below could be termed a secondmember, component, region, layer or section without departing from theteachings of the disclosed embodiments.

The terminology used herein is for describing particular embodimentsonly and is not intended to be limiting of the inventive concept. Asused herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”and/or “comprising” when used in this specification, specify thepresence of stated features, integers, steps, operations, members,elements, and/or groups thereof, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,members, elements, and/or groups thereof.

FIG. 1 is a view illustrating a signal processing apparatus 100,according to an embodiment. Referring to FIG. 1, the signal processingapparatus 100 includes a clock generator 110, a phase modulator 120, asignal synthesizer 130, a low-pass filter 140, and a sensor 150.

The clock generator 110 determines a phase of an input signal Drvgenerated by the sensor 150, and generates a clock signal (hereinafter,“clock”) CLK having a phase of a preset phase difference with respect tothe input signal Drv.

The preset phase difference may be represented differently, depending ona reference for the phase of the input signal Drv and a reference forthe phase of the clock CLK. For example, the reference for the phase ofthe input signal Drv may be 0° of a sin waveform, and the reference forthe phase of the clock CLK may be an instant at which the phase of theclock is increased from a low value to a high value. Therefore, thepreset phase difference may be 0°.

For example, the clock generator 110 generates a clock having the samephase as the phase of the input signal Drv using a self-oscillationloop. To achieve this, the self-oscillation loop feeds back the inputsignal Drv and phase-shifts the input signal Drv by a preset phasevalue. As a result, a feedback circuit operates in an unstable state togenerate a clock signal.

The clock generator 110 includes a phase shifter 111 to perform thephase-shifting by the preset phase. For example, the phase shifter 111phase-shifts the input signal Drv by 90°, and feeds back thephase-shifted input signal Drv to generate the clock CLK.

The phase modulator 120 shifts the phase of the clock generated by theclock generator 110 by a predetermined phase value and corrects thephase of the clock CLK. For example, the phase of the input signal Drvis shifted by the clock generator 110. However, due to reasons such asan occurrence condition of the clock CLK, and the like, the value of thephase shift performed by the clock generator 110 may not be changed.Therefore, the phase modulator 120 corrects a phase of a pre-generatedclock, thereby efficiently correcting the phase of the clock CLK.

Further, the phase modulator 120 determines a value by which to shiftthe phase of the clock signal based on an amplitude of the input signalDrv and an amplitude of noise included in the input signal Drv. Adetailed description of such a determination will be provided below withreference to FIG. 4.

The phase modulator 120 is connected to an amplifier 121 amplifying theclock CLK generated by the clock generator 110. The amplifier 121amplifies the clock CLK, such that the phase modulator 120 efficientlycorrects the phase of the clock CLK.

The signal synthesizer 130 synthesizes the clock CLK, having the phasecorrected by the phase modulator 120, and the input signal Drv. Forexample, the signal synthesizer 130 is a demodulator or a mixer thatreceives two signals and outputs a product of the two signals. Thus, thesignal synthesizer 130 multiplies the phase-corrected clock CLK and theinput signal Drv to generate a synthesized signal.

In a case in which a frequency of the input signal and a frequency ofthe clock are the same as each other, the output of the signalsynthesizer 130 is varied depending on a phase difference between thephase of the input signal Drv and the phase of the phase-corrected clockCLK. For example, in a case in which a phase difference of the inputsignal Drv and the phase-corrected clock CLK is 0° or 180°, the outputof the synthesizer 130 is significantly increased. For example, in acase in which the phase difference of the input signal Drv and thephase-corrected clock CLK is 90° or 270°, the output of the signalsynthesizer 130 is significantly decreased.

For example, the output of the signal synthesizer 130 for the inputsignal Drv is significantly increased, and the output of the signalsynthesizer 130 for noise is significantly decreased. A detaildescription of such an effect will be provided below with reference toFIGS. 3 and 4.

The low-pass filter 140 performs low-pass filtering on the signalsynthesized by the signal synthesizer 130. For example, a cut-offfrequency of the low-pass filter 140 is lower than basic frequencies ofthe input signal Drv and the clock CLK. Therefore, the low-pass filter140 outputs a direct current (DC) offset. For example, in a case inwhich the input signal Drv is the sensor signal, the sensing of thesensor 150 may be confirmed using the DC offset output from the low-passfilter 140.

The sensor 150 includes a sensor sensing the input signal Drv. Forexample, the signal processing apparatus 100 may be a sensor moduleconnected to the sensor. Therefore, the signal processing apparatus 100,according to an embodiment, may be included in an apparatus 200 fordriving a gyro sensor to be described below with reference to FIG. 2.

FIG. 2 is a view illustrating the apparatus 200 for driving a gyrosensor, according to an embodiment. Referring to FIG. 2, the apparatus200 includes a clock generator 210, a phase modulator 220, a signalsynthesizer 230, a low-pass filter 240, and a sensor 250. Further, theapparatus 200 drives a gyro sensor 300.

The clock generator 210 determines a phase of a driving signal Drv ofthe gyro sensor 300 and generates a clock CLK having a phase of a presetphase difference with respect to the driving signal Drv. The drivingsignal Drv is, for example, a signal sensed when the gyro sensor isrotated.

The phase modulator 220 shifts a phase of the clock CLK generated by theclock generator 210 by a predetermined phase and corrects the phase ofthe clock CLK. For example, the phase modulator 220 corrects the phaseso that a phase of the signal Drv sensed when the gyro sensor 300 isstopped and the phase of the clock CLK have a phase difference of 90°.

The signal synthesizer 230 synthesizes the clock CLK, having the phasecorrected by the phase modulator 220, and the driving signal Drv inorder to generate a synthesized signal.

The low-pass filter 240 performs low-pass filtering on the signalsynthesized by the signal synthesizer 230.

The sensor 250 senses driving displacements of three axes Wx, Wy, and Wzof the gyro sensor 300. Thus, the driving signal Drv includes threesignal components respectively corresponding to the three axes Wx, Wy,and Wz. Accordingly, the phase modulator 220 independently corrects thephase of the clock CLK for the three axes of Wx, Wy, and Wz the gyrosensor 300 to generate three respective phase-corrected clockscorresponding to the three axes Wx, Wy, and Wz. Therefore, the signalsynthesizer 230 synthesizes each component of the driving signal Drv forthe three axes of the gyro sensor 300 with phase-corrected clocks CLKhaving the phases independently corrected for the three axes.

The gyro sensor 300 may sense angular speed of a vibrating mass usingCoriolis force. For example, the gyro sensor 300 may sense angular speedof a mass vibrated by the driving signal Drv. A displacement by thevibration of the gyro sensor 300 may be used in the clock generator 210.

FIG. 3 is a graph illustrating a driving signal Drv when the gyro sensor300 is rotated, and a clock CLK. Referring to FIG. 3, the horizontalaxis shows a phase (deg), and the vertical axis shows a value of theclock CLK or the signal Drv when the gyro sensor 300 is rotated. Here, aphase difference between the phase of the clock CLK and the phase of thesignal Drv when the gyro sensor is rotated is 0° or 180°. Therefore, aproduct of the clock and the signal when the gyro sensor is rotated issignificantly increased, and sensitivity is significantly increased.

FIG. 4 is a graph illustrating a signal when the gyro sensor 200 isstopped, and a clock CLK. Referring to FIG. 4, the horizontal axis showsa phase (deg), and the vertical axis shows a value of the clock CLK orthe signal Drv when the gyro sensor 300 is stopped. Here, a phasedifference between the phase of the clock and the phase of the signalwhen the gyro sensor is stopped is 90° or 270°. Therefore, a product ofthe clock and the signal when the gyro sensor is rotated issignificantly decreased, and noise is significantly decreased.

Hereinafter, a relationship between the signal when the gyro sensor 300is stopped and noise will be described. Noise is affected by signalsoutput from the mass when the gyro sensor 300 is stopped.

As a first phenomenon, a mechanical quadrature signal presented byasymmetry of the mass, a spring, or the like affects the noise. Themechanical quadrature signal is a signal incurred because a perfectlysymmetrical structure cannot be practically formed.

As a second phenomenon, a signal presented by a non-proportional dampingincurred by an off-diagonal term of a damping matrix, affects the noise.Since the signal presented by the non-proportional damping has the samephase as that of Coriolis force and has a large structural influence, itmay be a difficult signal to cancel.

As a third phenomenon, an electrical cross coupling signal occurringwhile the driving signal Drv is sensed from a sensed signal, due to thedriving signal Drv electrically affecting the sensed signal, affects thenoise. The electronic coupling signal may have the same phase as that ofCoriolis force due to the affect by the driving signal Drv.

As a fourth phenomenon, a direct motion coupling signal incurred whilethe mass is directly moved by the driving signal Drv affects the noise.A difference between the direct motion coupling signal and themechanical quadrature signal is not driving force, but force having thesame phase as that of Coriolis force because the sensed mass is directlymoved by the driving signal Drv.

As a fifth phenomenon, a cross-coupling in electronics phenomenon inwhich various signals incurred due to parasitic capacitance orinductance incurred in a circuit affect the sensed signal, affect noise.Further, the cross-coupling in electronics may exist as signals havingthe same phase as that of Coriolis force due to various signalcomponents.

The remaining signals and phenomena (the second signal to the fifthphenomenon) described above except for the mechanical quadrature signalmay be defined as internal and external interference signals of thesensor. A phase of the mechanical quadrature signal and a phase of thesignal Drv when the gyro sensor 300 is stopped may have a phasedifference of 0° or 180°. A phase of the interference signal and thephase of the signal Drv when the gyro sensor is stopped may have a phasedifference of 90° or 270°.

In a case in which amplitude of the mechanical quadrature signal isgreater than amplitude of the interference signal, the noise may bealmost affected by the mechanical quadrature signal. Therefore, a phasedifference between the phase of the signal Drv when the gyro sensor isstopped and a phase of noise may be close to 0° or 180°.

Further, in a case in which amplitude of the mechanical quadraturesignal is similar to or less than amplitude of the interference signal,an influence of the mechanical quadrature signal on the noise may besmall. Therefore, the phase difference between the phase of the signalwhen the gyro sensor is stopped and the phase of noise may be differentfrom 0° or 180°.

Therefore, in a case in which the phase of the clock CLK is notcorrected by the phase modulator 220 included in the apparatus 200, aS/N ratio of the gyro sensor 300 may be deteriorated.

FIG. 5 is a graph illustrating a phase distortion of a signal Drv whenthe gyro sensor 300 is stopped. Referring to FIG. 5, the horizontal axisshows a time, and the vertical axis shows values of the driving signalDrv when the gyro sensor 300 is rotated and the signal Drv when the gyrosensor is stopped. For example, a phase difference between a phase ofthe driving signal Drv when the gyro sensor 300 is rotated and a phaseof the signal Drv when the gyro sensor 300 is stopped may be 110°. Thatis, FIG. 5 illustrates a case in which the phase difference between thephase of the signal Drv when the gyro sensor is stopped and the phase ofnoise is different from 0° or 180°.

The phase distortion is determined by the following Equation 1.

$\begin{matrix}{{noise} = \sqrt{\frac{1}{N}{\sum\limits_{k}^{N}\;( {\frac{2}{\pi}G_{1}{G_{2}( {{V_{q}{\sin( P_{q} )}{\phi( t_{k} )}} - {{\lambda( t_{k} )}{\cos( P_{q} )}}} )}} )^{2}}}} & \lbrack {{Equation}\mspace{14mu} 1} \rbrack\end{matrix}$(A_(q): quadrature Signal Amplitude Average, λ(t): quadrature SignalAmplitude Change P_(q): quadrature Signal Phase Average, φ(t):quadrature Signal Phase Change)

Therefore, the phase of the clock CLK is corrected by the phasemodulator 220 included in the apparatus 200, such that the S/N ratio ofthe gyro sensor 300 is improved.

For example, in a case in which the phase modulator 200 shifts the phaseby 15° to 30°, sensitivity may be increased to a maximum of 30%. Forexample, in a case in which the phase modulator 200 shifts the phase by15° to 30°, noise may be decreased to a minimum of 30%.

For example, in a case in which the phase modulator 200 shifts the phaseby 15° to 30°, noise density may be decreased to a maximum of 70%.

As set forth above, according to the embodiments disclosed herein, theS/N ratio of a gyro sensor may be improved.

The apparatuses, units, modules, devices, and other components (e.g.,the clock generators 110 and 210, the phase shifter 111, the amplifier121, the phase modulators 120 and 220, the synthesizers 130 and 230, theLPFs 140 and 240, the sensors 150 and 250 and the gyro sensor 300)illustrated in FIGS. 1 and 2 that perform the operations describedherein are implemented by hardware components. Examples of hardwarecomponents include controllers, sensors, generators, drivers, and anyother electronic components known to one of ordinary skill in the art.In one example, the hardware components are implemented by one or moreprocessors or computers. A processor or computer is implemented by oneor more processing elements, such as an array of logic gates, acontroller and an arithmetic logic unit, a digital signal processor, amicrocomputer, a programmable logic controller, a field-programmablegate array, a programmable logic array, a microprocessor, or any otherdevice or combination of devices known to one of ordinary skill in theart that is capable of responding to and executing instructions in adefined manner to achieve a desired result. In one example, a processoror computer includes, or is connected to, one or more memories storinginstructions or software that are executed by the processor or computer.Hardware components implemented by a processor or computer executeinstructions or software, such as an operating system (OS) and one ormore software applications that run on the OS, to perform the operationsdescribed herein with respect to FIGS. 1 and 2. The hardware componentsalso access, manipulate, process, create, and store data in response toexecution of the instructions or software. For simplicity, the singularterm “processor” or “computer” may be used in the description of theexamples described herein, but in other examples multiple processors orcomputers are used, or a processor or computer includes multipleprocessing elements, or multiple types of processing elements, or both.In one example, a hardware component includes multiple processors, andin another example, a hardware component includes a processor and acontroller. A hardware component has any one or more of differentprocessing configurations, examples of which include a single processor,independent processors, parallel processors, single-instructionsingle-data (SISD) multiprocessing, single-instruction multiple-data(SIMD) multiprocessing, multiple-instruction single-data (MISD)multiprocessing, and multiple-instruction multiple-data (MIMD)multiprocessing.

Instructions or software to control a processor or computer to implementthe hardware components and perform the methods as described above arewritten as computer programs, code segments, instructions or anycombination thereof, for individually or collectively instructing orconfiguring the processor or computer to operate as a machine orspecial-purpose computer to perform the operations performed by thehardware components and the methods as described above. In one example,the instructions or software include machine code that is directlyexecuted by the processor or computer, such as machine code produced bya compiler. In another example, the instructions or software includehigher-level code that is executed by the processor or computer using aninterpreter. Programmers of ordinary skill in the art can readily writethe instructions or software based on the block diagrams illustrated inthe drawings and the corresponding descriptions in the specification,which disclose algorithms for performing the operations performed by thehardware components as described above.

The instructions or software to control a processor or computer toimplement the hardware components and perform the methods as describedabove, and any associated data, data files, and data structures, arerecorded, stored, or fixed in or on one or more non-transitorycomputer-readable storage media. Examples of a non-transitorycomputer-readable storage medium include read-only memory (ROM),random-access memory (RAM), flash memory, CD-ROMs, CD-Rs, CD+Rs, CD-RWs,CD+RWs, DVD-ROMs, DVD-Rs, DVD+Rs, DVD-RWs, DVD+RWs, DVD-RAMs, BD-ROMs,BD-Rs, BD-R LTHs, BD-REs, magnetic tapes, floppy disks, magneto-opticaldata storage devices, optical data storage devices, hard disks,solid-state disks, and any device known to one of ordinary skill in theart that is capable of storing the instructions or software and anyassociated data, data files, and data structures in a non-transitorymanner and providing the instructions or software and any associateddata, data files, and data structures to a processor or computer so thatthe processor or computer can execute the instructions. In one example,the instructions or software and any associated data, data files, anddata structures are distributed over network-coupled computer systems sothat the instructions and software and any associated data, data files,and data structures are stored, accessed, and executed in a distributedfashion by the processor or computer.

While this disclosure includes specific examples, it will be apparent toone of ordinary skill in the art that various changes in form anddetails may be made in these examples without departing from the spiritand scope of the claims and their equivalents. The examples describedherein are to be considered in a descriptive sense only, and not forpurposes of limitation. Descriptions of features or aspects in eachexample are to be considered as being applicable to similar features oraspects in other examples. Suitable results may be achieved if thedescribed techniques are performed in a different order, and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner, and/or replaced or supplemented by othercomponents or their equivalents. Therefore, the scope of the disclosureis defined not by the detailed description, but by the claims and theirequivalents, and all variations within the scope of the claims and theirequivalents are to be construed as being included in the disclosure.

What is claimed is:
 1. A signal processing apparatus comprising: a clockgenerator configured to generate a clock signal having a phase based ona phase of an input signal; a phase modulator configured to shift thephase of the clock signal to generate a phase-shifted clock signal; anda signal synthesizer configured to synthesize the phase-shifted clocksignal and the input signal to generate a synthesized signal, whereinthe phase modulator is configured to determine a value by which to shiftthe phase of the clock signal based on an amplitude of the input signaland an amplitude of noise included in the input signal.
 2. The signalprocessing apparatus of claim 1, wherein the clock generator isconfigured to generate the clock signal using a self-oscillation loopsuch that the phase of the clock signal is the same as the phase of theinput signal.
 3. The signal processing apparatus of claim 1, furthercomprising a low-pass filter configured to perform low-pass filtering onthe synthesized signal.
 4. An apparatus for driving a gyro sensor, theapparatus comprising: a clock generator configured to generate a clocksignal having a phase based on a phase of a driving signal; a phasemodulator configured to shift the phase of the clock signal to generatea phase-shifted clock signal; a signal synthesizer configured tosynthesize the phase-shifted clock signal to generate a synthesizedsignal; and a low-pass filter configured to perform low-pass filteringon the synthesized signal.
 5. The apparatus of claim 4, wherein: theclock generator comprises a phase shifter configured to phase-shift thedriving signal by 90°; and the phase shifter is configured tophase-shift a feedback signal including driving displacement informationof the gyro sensor by 90°, and feed back the phase-shifted feedbacksignal to the driving signal to generate the clock signal.
 6. Theapparatus of claim 4, wherein: the phase modulator includes an amplifierconfigured to amplify the clock signal generated by the clock generator;the phase modulator is configured to perform phase correction such thatthe phase of the driving signal sensed when the gyro sensor is stoppedand the phase of the clock signal have a phase difference of 90°; andthe phase modulator is configured to perform the phase correction suchthat the phase of the driving signal sensed when the gyro sensor isrotated and the phase of the clock signal have a phase difference of 0°.7. The apparatus of claim 4, further comprising a sensor configured tosense driving displacements of three axes of the gyro sensor, whereinthe phase modulator is configured to independently shift the phase ofthe clock signal for the three axes, and wherein the signal synthesizeris configured to synthesize corresponding components of the drivingsignal for the three axes with the phase-shifted clock signal.
 8. Theapparatus of claim 4, wherein the phase modulator is configured todetermine a value by which to shift the phase of the clock signal basedon an amplitude of the driving signal and an amplitude of noise includedin the driving signal.
 9. A signal processing method, comprising:generating, at a clock generator, a clock signal having a phase based ona phase of an input signal; shifting, at a phase modulator, the phase ofthe clock signal to generate a phase-shifted clock signal; combiningphase-shifted clock signal and the input signal to generate a combinedsignal; and performing low-pass filtering on the combined signal. 10.The method of claim 9, wherein the combining of the phase-shifted clocksignal and the input signal comprises multiplying the phase-shiftedclock signal and the input signal.
 11. The method of claim 9, whereinthe input signal is generated by a gyroscope.
 12. The method of claim 9,further comprising generating the clock signal using a self-oscillationloop.
 13. The method of claim 9, wherein the phase modulator isconfigured to determine a value by which to shift the phase of the clocksignal based on an amplitude of the input signal and an amplitude ofnoise included in the input signal.